Nucleoside derivatives for treating hepatitis C virus infection

ABSTRACT

Disclosed are compounds, compositions and methods for treating viral infections caused by a flaviviridae family virus, such as hepatitis C virus.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/676,956, filed on Sep. 30, 2003, which application claimsthe benefit of U.S. Provisional Application Ser. No. 60/443,169, filedJan. 29, 2003 and U.S. Provisional Application Ser. No. 60/415,222,filed Sep. 30, 2002. Each of these applications are incorporated hereinby reference in their entirety.

FIELD OF THE INVENTION

The invention relates to the field of pharmaceutical chemistry, inparticular to compounds, compositions and methods for treating viralinfections in mammals mediated, at least in part, by a virus in theflaviviridae family of viruses. This invention also relates tocompounds, compositions and methods for treating hepatitis C viralinfections.

REFERENCES

The following publications are cited in this application as superscriptnumbers:

-   1. Chen, et al., Med. Assoc., 25(1):6-12 (1996)-   2. Cornberg, et al., “Hepatitis C: therapeutic perspectives.” Forum    (Genova), 11(2):154-62 (2001)-   3. Dymock, et al., Antivir. Chem. Chemother. 11(2):79-96 (2000)-   4. Devos, et al., International Patent Application Publication No.    WO 02/18404 A2, published 7 Mar. 2002-   5. Sommadossi, et al., International Patent Application Publication    No. WO 01/90121, published 23 May 2001-   6. Carroll, et al., International Patent Application Publication No.    WO 02/057425-   7. Seela, F.; Steker, H., Liebigs Ann. Chem., p. 1576 (1983).-   8. Li, N-.S.; Tang, X.-Q.; Piccirilli, J. A., Organic Letters,    3(7):1025 (2001).

All of the above publications are herein incorporated by reference intheir entirety to the same extent as if each individual publication wasspecifically and individually indicated to be incorporated by referencein its entirety.

State of the Art

Hepatitis C virus (HCV) causes a liver damaging infection that can leadto cirrhosis, liver failure or liver cancer, and eventually death. HCVis an enveloped virus containing a positive-sense single-stranded RNAgenome of approximately 9.4 kb, and has a virion size of 30-60 nm.¹

HCV is a major causative agent for post-transfusion and for sporadicnon-A, non-B hepatitis. Infection by HCV is insidious in a highproportion of chronically infected (and infectious) carriers who may notexperience clinical symptoms for many years.

HCV is difficult to treat and it is estimated that there are 500 millionpeople infected with it worldwide. No effective immunization iscurrently available, and hepatitis C can only be controlled by otherpreventive measures such as improvement in hygiene and sanitaryconditions and interrupting the route of transmission.

At present, the only acceptable treatment for chronic hepatitis C isinterferon (IFN-alpha) and this requires at least six (6) months oftreatment and/or ribavarin, which can inhibit viral replication ininfected cells and also improve liver function in some people.

IFN-alpha belongs to a family of naturally occurring small proteins withcharacteristic biological effects such as antiviral, immunoregulatoryand antitumoral activities that are produced and secreted by most animalnucleated cells in response to several diseases, in particular, viralinfections. IFN-alpha is an important regulator of growth anddifferentiation affecting cellular communication and immunologicalcontrol. Treatment of HCV with interferon, however, has limited longterm efficacy with a response rate about 25%. In addition, treatment ofHCV with interferon has frequently been associated with adverse sideeffects such as fatigue, fever, chills, headache, myalgias, arthralgias,mild alopecia, psychiatric effects and associated disorders, autoimmunephenomena and associated disorders and thyroid dysfunction.

Ribavirin (1-β-D-ribofuranosyl-1H-1,2,4-triazole-3-carboxamide), aninhibitor of inosine 5′-monophosphate dehydrogenase (IMPDH), enhancesthe efficacy of IFN-alpha in the treatment of HCV. Despite theintroduction of ribavirin, more than 50% of the patients do noteliminate the virus with the current standard therapy ofinterferon-alpha (IFN) and ribavirin. By now, standard therapy ofchronic hepatitis C has been changed to the combination of PEG-IFN plusribavirin. However, a number of patients still have significant sideeffects, primarily related to ribavirin. Ribavirin causes significanthemolysis in 10-20% of patients treated at currently recommended doses,and the drug is both teratogenic and embryotoxic.

Other approaches are being taken to combat the virus. They include, forexample, application of antisense oligonucleotides or ribozymes forinhibiting HCV replication. Furthermore, low-molecular weight compoundsthat directly inhibit HCV proteins and interfere with viral replicationare considered as attractive strategies to control HCV infection. NS3/4Aserine protease, ribonucleic acid (RNA) helicase, RNA-dependent RNApolymerase are considered as potential targets for new drugs.^(2,3)

Devos, et al.⁴ describes purine and pyrimidine nucleoside derivativesand their use as inhibitors of HCV RNA replication.

Sommadossi, et al.⁵ describes 1′, 2′ or 3′-modified nucleosides andtheir use for treating a host infected with HCV.

Given the fact of the worldwide epidemic level of HCV, there is a strongneed for new effective drugs for HCV treatment. The present inventionprovides nucleoside derivatives for treating HCV infections.

SUMMARY OF THE NTION

This invention is directed to novel compounds that are useful in thetreatment of HCV in mammals. Specifically, in one aspect, the compoundsof this invention are represented by Formula I below:

wherein:

W, W¹ and W² are independently selected from the group consisting ofhydrogen and a pharmaceutically acceptable prodrug;

R is selected from the group consisting of hydrogen or (C₁-C₃)alkyl;

R¹ is selected from the group consisting of hydrogen, alkyl, substitutedalkyl, alkenyl, substituted alkenyl, alkynyl and substituted alkynyl;

Y is a bond, —CH₂— or —O—;

Y′ is selected from the group consisting of hydrogen, halo, hydroxyl,thioalkyl, amino and substituted amino;

Z is selected from the group consisting of acyl, cyano, carboxyl,carboxyl ester, —C(O)NR²⁰R²¹, halo, —B(OH)₂, —C(═NR²)R³, nitro, alkenyl,substituted alkenyl, acetylenyl and substituted acetylenyl of theformula —C≡C—R⁴;

where R² is selected from the group consisting of hydrogen, —OH, —OR⁵amino, substituted amino, and (C₁-C₂)alkyl, where R⁵ is selected fromthe group consisting of alkyl and substituted alkyl;

R³ is selected from the group consisting of hydrogen, alkyl, substitutedalkyl, amino and substituted amino;

R⁴ is selected from the group consisting of hydrogen, phenyl,substituted phenyl, heteroaryl, substituted heteroaryl, —Si(R⁸)₃,carboxyl, carboxyl esters, and —C(O)NR⁶R⁷ where R⁶ and R⁷ areindependently hydrogen, alkyl or R⁶ and R⁷ together with the nitrogenatom pendent thereto are joined to form a heterocyclic, substitutedheterocyclic, heteroaryl or substituted heteroaryl group;

each R⁸ is independently (C₁-C₄)alkyl or phenyl; and

R²⁰ and R²¹ are independently hydrogen, alkyl, substituted alkyl, aryl,substituted aryl, heteroaryl, substituted heteroaryl, heterocyclic andsubstituted heterocyclic or R²⁰ and R²¹, together with the nitrogen atompendent thereto form a heterocyclic or substituted heterocyclic group;

or pharmaceutically acceptable salts thereof.

In one preferred embodiment, W is preferably selected from the groupconsisting of hydrogen, monophosphate, diphosphate, and triphosphate andW¹ and W² are independently hydrogen or acyl. Preferred acyl groupsinclude acetyl and trimethylacetyl, and acyl groups derived from aminoacids.

In another aspect, the compounds of this invention are represented byFormula II below:

where R, W and Z are as defined above;

or pharmaceutically acceptable salts thereof.

In preferred embodiment, W is preferably selected from the groupconsisting of hydrogen, monophosphate, diphosphate, and triphosphate.

In the compounds of formula I and II above, Z is preferably selectedfrom the group consisting of acyl, nitro, halo, cyano, —C(═NR²)R³,acetylenyl and substituted acetylenyl of the formula —C≡C—R⁴ where R²,R³ and R⁴ are as defined above.

Even more preferably, Z is selected from formyl, nitro, bromo, iodo, and—C═C—R⁴ where R⁴ is selected from H, phenyl, and —Si(CH₃)₃.

In one embodiment, when Z is an alkenyl or substituted alkenyl group,such groups are preferably in the cis orientation if the substituent hasa cis/trans relationship.

Compounds included within the scope of this invention include, forexample, those set forth below (including pharmaceutically acceptablesalts thereof) in Table I: TABLE I I

# Structure Name 1

1-(6-hydroxylamino-7-ethynyl-7-deaza- purin-9-yl)-2-methyl-β-D-ribo-furanose 2

1-(6-hydroxylamino-7-(2-phenylethyn-1-yl)-7-deaza-purin-9-yl)-2-methyl-β-D-ribo- furanose 3

1-(6-hydroxylamino-7-(2-(pyridin-2-yl)-eth-yn-1-yl)-7-deazapurin-9-yl)-2-meth- yl-β-D-ribofuranose 4

1-(6-hydroxylamino-7-(2-(4-fluoro-phenyl)ethyn-1-yl)-7-deazapurin-9-yl)-2-meth- yl-β-D-ribofuranose 5

1-(6-hydroxylamino-7-(2-(4-meth- ylphenyl)ethyn-1-yl)-7-deaza-purin-9-yl)-2-methyl-β-D-ribofuranose 6

1-(6-hydroxylamino-7-(2-carboxylethyn-1-yl)-7-deaza-purin-9-yl)-2-methyl-β-D-ribo- furanose 7

1-(6-hydroxylamino-7-(2-ethylcarboxylethyn-1-yl)-7-deazapurin-9-yl)-2-meth- yl-β-D-ribofuranose 8

1-(6-hydroxylamino-7-(2-carbox-amidoethyn-1-yl)-7-deazapurin-9-yl)-2-meth- yl-β-D-ribofuranose 9

1-(6-hydroxylamino-7-(2-tri-methylsilylethyn-1-yl)-7-deazapurin-9-yl)-2-meth- yl-β-D-ribofuranose 10

1-(6-hydroxylamino-7-ethenyl-7-deaza-purin-9-yl)-2-methyl-β-D-ribofuranose 11

1-(6-hydroxylamino-7-formyl-7-deaza-purin-9-yl)-2-methyl-β-D-ribofuranose 12

1-(6-hydroxylamino-7-(carbalde- hyde oxime))-7-deazapurin-9-yl)-2-meth-yl-β-D-ribofuranose; 13

1-(6-hydroxylamino-7-(boronic acid)-7-deaza-purin-9-yl)-2-methyl-β-D-ribo- furanose 14

1-(6-hydroxylamino-7-(2,2-di- fluorovinyl)-7-deazapurin-9-yl)-2-meth-yl-β-D-ribofuranose 15

1-(6-hydroxylamino-7-(2-cis- methoxyvinyl)-7-deazapurin-9-yl)-2-meth-yl-β-D-ribofuranose 16

1-(6-hydroxylamino-7-nitro-7-deaza-purin-9-yl)-2-methyl-β-D-ribofuranose 17

1-(6-hydroxylamino-7-cyano-7-deaza- purin-9-yl)-2-methyl-β-D-ribofuranse18

1-(6-methoxyamino-7-ethynyl-7-deaza- purin-9-yl)-2-methyl-β-D-ribo-furanose 19

1-(6-methoxyamino-7-nitro-7-deaza- purin-9-yl)-2-methyl-β-D-ribofuranose20

1-(6-methoxyamino-7-formyl-7-deaza-purin-9-yl)-2-methyl-β-D-ribofuranose

This invention is also directed to pharmaceutical compositionscomprising a pharmaceutically acceptable diluent and a therapeuticallyeffective amount of a compound of this invention or mixtures of one ormore of such compounds.

This invention is still further directed to methods for treating a viralinfection mediated at least in part by a virus in the flaviviridaefamily of viruses, such as HCV, in mammals which methods compriseadministering to a mammal, that has been diagnosed with said viralinfection or is at risk of developing said viral infection, apharmaceutical composition comprising a pharmaceutically acceptablediluent and a therapeutically effective amount of compounds of thisinvention or mixtures of one or more of such compounds.

DETAILED DESCRIPTION OF THE INVENTION

The invention is directed to compounds, compositions and methods fortreating flaviviridae viruses, such as hepatitis C virus infections.However, prior to describing this invention in detail, the followingterms will first be defined:

Definitions

Unless otherwise limited by the term as used elsewhere herein, thefollowing terms have the following meanings:

“Alkyl” refers to alkyl groups having from 1 to 5 carbon atoms and morepreferably 1 to 3 carbon atoms. The alkyl group may contain linear orbranched carbon chains. This term is exemplified by groups such asmethyl, ethyl, n-propyl, iso-propyl, n-butyl, t-butyl, n-pentyl and thelike. The term C₁-C₂ alkyl refers to an alkyl group having one or twocarbon atoms.

“Substituted alkyl” refers to an alkyl group having from 1 to 3, andpreferably 1 to 2, substituents selected from the group consisting ofalkoxy, substituted alkoxy, acyl, acylamino, acyloxy, amino, substitutedamino, aminoacyl, aryl, substituted aryl, aryloxy, substituted aryloxy,cyano, halogen, hydroxyl, nitro, carboxyl, carboxyl esters, cycloalkyl,substituted cycloalkyl, heteroaryl, substituted heteroaryl,heterocyclic, and substituted heterocyclic.

“Alkoxy” refers to the group “alkyl-O-” which includes, by way ofexample, methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, t-butoxy,sec-butoxy, n-pentoxy and the like.

“Substituted alkoxy” refers to the group “substituted alkyl-O-”.

“Acyl” refers to the groups H—C(O)—, alkyl-C(O)—, substitutedalkyl-C(O)—, alkenyl-C(O)—, substituted alkenyl-C(O)—, alkynyl-C(O)—,substituted alkynyl-C(O)—, cycloalkyl-C(O)—, substitutedcycloalkyl-C(O)—, aryl-C(O)—, substituted aryl-C(O)—, heteroaryl-C(O)—,substituted heteroaryl-C(O), heterocyclic-C(O)— and substitutedheterocyclic-C(O)— wherein alkyl, substituted alkyl, alkenyl,substituted alkenyl, alkynyl, substituted alkynyl, cycloalkyl,substituted cycloalkyl, aryl, substituted aryl, heteroaryl, substitutedheteroaryl, heterocyclic and substituted heterocyclic are as definedherein.

“Acylamino” refers to the group —C(O)NR¹⁰R¹⁰ where each R¹⁰ isindependently selected from the group consisting of hydrogen, alkyl,substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substitutedalkynyl, aryl, substituted aryl, cycloalkyl, substituted cycloalkyl,heteroaryl, substituted heteroaryl, heterocyclic, substitutedheterocyclic and where each R¹⁰ is joined to form together with thenitrogen atom a heterocyclic or substituted heterocyclic ring whereinalkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl,substituted alkynyl, cycloalkyl, substituted cycloalkyl, aryl,substituted aryl, heteroaryl, substituted heteroaryl, heterocyclic andsubstituted heterocyclic are as defined herein.

“Acyloxy” refers to the groups alkyl-C(O)O—, substituted alkyl-C(O)O—,alkenyl-C(O)O—, substituted alkenyl-C(O)O—, alkynyl-C(O)O—, substitutedalkynyl-C(O)O—, aryl-C(O)O—, substituted aryl-C(O)O—, cycloalkyl-C(O)O—,substituted cycloalkyl-C(O)O—, heteroaryl-C(O)O—, substitutedheteroaryl-C(O)O—, heterocyclic-C(O)O—, and substitutedheterocyclic-C(O)O— wherein alkyl, substituted alkyl, alkenyl,substituted alkenyl, alkynyl, substituted alkynyl, cycloalkyl,substituted cycloalkyl, aryl, substituted aryl, heteroaryl, substitutedheteroaryl, heterocyclic and substituted heterocyclic are as definedherein.

“Alkenyl” refers to alkenyl group preferably having from 2 to 6 carbonatoms and more preferably 2 to 4 carbon atoms and having at least 1 andpreferably from 1-2 sites of alkenyl unsaturation. Such groups areexemplified by vinyl, allyl, but-3-en-1-yl, and the like.

“Substituted alkenyl” refers to alkenyl groups having from 1 to 3substituents, and preferably 1 to 2 substituents, selected from thegroup consisting of alkoxy, substituted alkoxy, acyl, acylamino,acyloxy, amino, substituted amino, aminoacyl, aryl, substituted aryl,aryloxy, substituted aryloxy, cyano, halogen, hydroxyl, nitro, carboxyl,carboxyl esters, cycloalkyl, substituted cycloalkyl, heteroaryl,substituted heteroaryl, heterocyclic, and substituted heterocyclic withthe proviso that any hydroxyl substitution is not attached to a vinyl(unsaturated) carbon atom.

“Alkynyl” refers to alkynyl group preferably having from 2 to 6 carbonatoms and more preferably 2 to 3 carbon atoms and having at least 1 andpreferably from 1-2 sites of alkynyl unsaturation. A preferred alkynylis C₂ alkynyl which is sometimes referred to herein as acetylenyl:—C≡CH.

“Substituted alkynyl” refers to alkynyl groups having from 1 to 3substituents, and preferably 1 to 2 substituents, selected from thegroup consisting of alkoxy, substituted alkoxy, acyl, acylamino,acyloxy, amino, substituted amino, aminoacyl, aryl, substituted aryl,aryloxy, substituted aryloxy, cyano, halogen, hydroxyl, nitro, carboxyl,carboxyl esters, cycloalkyl, substituted cycloalkyl, heteroaryl,substituted heteroaryl, heterocyclic, and substituted heterocyclic. Apreferred substituted alkynyl is substituted acetylenyl which can berepresented by the formula: —C—CR⁴ where R⁴ is as defined herein.

“Amino” refers to the group —NH₂.

“Substituted amino” refers to the group —NR′R″ where R′ and R″ areindependently selected from the group consisting of hydrogen, alkyl,substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substitutedalkynyl, aryl, substituted aryl, cycloalkyl, substituted cycloalkyl,heteroaryl, substituted heteroaryl, heterocyclic, substitutedheterocyclic and where R′ and R″ are joined, together with the nitrogenbound thereto to form a heterocyclic or substituted heterocylic groupprovided that R′ and R″ are both not hydrogen. When R′ is hydrogen andR″ is alkyl, the substituted amino group is sometimes referred to hereinas alkylamino. When R′ and R″ are alkyl, the substituted amino group issometimes referred to herein as dialkylamino.

“Aminoacyl” refers to the groups —NR¹¹C(O)alkyl, —NR¹¹C(O)substitutedalkyl, —NR¹¹C(O)cycloalkyl, —NR¹¹C(O)substituted cycloalkyl,—NR¹¹C(O)alkenyl, —NR¹¹C(O)substituted alkenyl, —NR¹¹C(O)alkynyl,—NR¹¹C(O)substituted alkynyl, —NR¹¹C(O)aryl, —NR¹¹C(O)substituted aryl,—NR¹¹C(O)heteroaryl, —NR¹¹C(O)substituted heteroaryl,—NR¹¹C(O)heterocyclic, and —NR¹¹C (O)substituted heterocyclic where R¹¹is hydrogen or alkyl and wherein alkyl, substituted alkyl, alkenyl,substituted alkenyl, alkynyl, substituted alkynyl, cycloalkyl,substituted cycloalkyl, aryl, substituted aryl, heteroaryl, substitutedheteroaryl, heterocyclic and substituted heterocyclic are as definedherein.

“Aryl” or “Ar” refers to a monovalent aromatic carbocyclic group of from6 to 14 carbon atoms having a single ring (e.g., phenyl) or multiplecondensed rings (e.g., naphthyl or anthryl) which condensed rings may ormay not be aromatic (e.g., 2-benzoxazolinone,2H-1,4-benzoxazin-3(4H)-one-7-yl, and the like) provided that the pointof attachment is at an aromatic carbon atom. Preferred aryls includephenyl and naphthyl.

“Substituted aryl” refers to aryl groups including phenyl groups(sometimes referred to herein as “substituted phenyl”) which aresubstituted with from 1 to 3 substituents, and preferably 1 to 2substituents, selected from the group consisting of hydroxy, acyl,acylamino, acyloxy, alkyl, substituted alkyl, alkoxy, substitutedalkoxy, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl,amino, substituted amino, aminoacyl, aryl, substituted aryl, aryloxy,substituted aryloxy, cycloalkoxy, substituted cycloalkoxy, carboxyl,carboxyl esters, cyano, thiol, thioalkyl, substituted thioalkyl,thioaryl, substituted thioaryl, thioheteroaryl, substitutedthioheteroaryl, thiocycloalkyl, substituted thiocycloalkyl,thioheterocyclic, substituted thioheterocyclic, cycloalkyl, substitutedcycloalkyl, halo, nitro, heteroaryl, substituted heteroaryl,heterocyclic, substituted heterocyclic, heteroaryloxy, substitutedheteroaryloxy, heterocyclyloxy, and substituted heterocyclyloxy.

“Aryloxy” refers to the group aryl-O— that includes, by way of example,phenoxy, naphthoxy, and the like.

“Substituted aryloxy” refers to substituted aryl-O— groups.

“Carboxyl” refers to —COOH or salts therof.

“Carboxyl esters” refers to the groups C(O)O-alkyl, —(O)O-substitutedalkyl, —C(O)Oaryl, and —C(O)O-substituted aryl wherein alkyl,substituted alkyl, aryl and substituted aryl are as defined herein.

“Cycloalkyl” refers to cyclic alkyl groups of from 3 to 10 carbon atomshaving single or multiple cyclic rings including, by way of example,adamantyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclooctyl and thelike.

“Substituted cycloalkyl” refers to an cycloalkyl group, having from 1 to5 substituents selected from the group consisting of oxo (═O), thioxo(═S), alkoxy, substituted alkoxy, acyl, acylamino, acyloxy, amino,substituted amino, aminoacyl, aryl, substituted aryl, aryloxy,substituted aryloxy, cyano, halogen, hydroxyl, nitro, carboxyl, carboxylesters, cycloalkyl, substituted cycloalkyl, heteroaryl, substitutedheteroaryl, heterocyclic, and substituted heterocyclic.

“Cycloalkoxy” refers to —O-cycloalkyl groups.

“Substituted cycloalkoxy” refers to —O-substituted cycloalkyl groups.

“Halo” or “halogen” refers to fluoro, chloro, bromo and iodo andpreferably is fluoro or chloro.

“Heteroaryl” refers to an aromatic group of from 1 to 10 carbon atomsand 1 to 4 heteroatoms selected from the group consisting of oxygen,nitrogen, sulfur, —S(O)—, and —S(O)₂— within the ring. Such heteroarylgroups can have a single ring (e.g., pyridyl or furyl) or multiplecondensed rings (e.g., indolizinyl or benzothienyl) wherein thecondensed rings may or may not be aromatic and/or contain a heteroatomprovided that the point of attachment is through an atom of the aromaticheteroaryl group. Preferred heteroaryls include pyridyl, pyrrolyl,indolyl, thiophenyl, and furyl.

“Substituted heteroaryl” refers to heteroaryl groups that aresubstituted with from 1 to 3 substituents selected from the same groupof substituents defined for substituted aryl.

“Heteroaryloxy” refers to the group —O-heteroaryl and “substitutedheteroaryloxy” refers to the group —O-substituted heteroaryl.

“Heterocycle” or “heterocyclic” or “heterocycloalkyl” refers to asaturated or unsaturated, but not heteroaromatic, group having a singlering or multiple condensed rings, from 1 to 10 carbon atoms and from 1to 4 hetero atoms selected from the group consisting of nitrogen,oxygen, sulfur, —S(O)— and —S(O)₂— within the ring wherein, in fusedring systems, one or more the rings can be cycloalkyl, aryl orheteroaryl provided that the point of attachment is through theheterocyclic ring.

“Substituted heterocyclic” or “substituted heterocycloalkyl” refers toheterocycle groups that are substituted with from 1 to 3 of the samesubstituents as defined for substituted cycloalkyl.

Examples of heterocycles and heteroaryls include, but are not limitedto, azetidine, pyrrole, imidazole, pyrazole, pyridine, pyrazine,pyrimidine, pyridazine, indolizine, isoindole, indole, dihydroindole,indazole, purine, quinolizine, isoquinoline, quinoline, phthalazine,naphthylpyridine, quinoxaline, quinazoline, cinnoline, pteridine,carbazole, carboline, phenanthridine, acridine, phenanthroline,isothiazole, phenazine, isoxazole, phenoxazine, phenothiazine,imidazolidine, imidazoline, piperidine, piperazine, indoline,phthalimide, 1,2,3,4-tetrahydro-isoquinoline,4,5,6,7-tetrahydrobenzo[b]thiophene, thiazole, thiazolidine, thiophene,benzo[b]thiophene, morpholinyl, thiomorpholinyl (also referred to asthiamorpholinyl), piperidinyl, pyrrolidine, tetrahydrofuranyl, and thelike.

“Heterocyclyloxy” refers to the group —O-heterocyclic and “substitutedheterocyclyloxy” refers to the group —O-substituted heterocyclic.

“Phosphate” refers to the groups —P(O)(OH)₂ (monophosphate),—P(O)(OH)OP(O)(OH)₂ (diphosphate) and —P(O)(OH)OP(O)(OH)OP(O)(OH)₂(triphosphate) or salts thereof including partial salts thereof

“Phosphonate” refers to the groups —P(O)(R¹²)(OH) or —P(O)(R¹²)(OR¹³) orsalts thereof including partial salts thereof, wherein each R¹² isindependently selected from hydrogen, alkyl, substituted alkyl,carboxylic acid, and carboxyl ester and R¹³ is alkyl or substitutedalkyl.

“Sulfonate ester” refers to the groups —SO₂OR¹⁴ where R¹⁴ is selectedfrom the group consisting of alkyl, substituted alkyl, alkenyl,substituted alkenyl, aryl, substituted aryl, heteroaryl, substitutedheteroaryl, heterocyclic and substituted heterocyclic.

“Thiol” refers to the group —SH.

“Thioalkyl” or “alkylthioether” or “thioalkoxy” refers to the group—S-alkyl.

“Substituted thioalkyl” or “substituted alkylthioether” or “substitutedthioalkoxy” refers to the group —S-substituted alkyl.

“Thiocycloalkyl” refers to the groups —S-cycloalkyl and “substitutedthiocycloalkyl” refers to the group —S-substituted cycloalkyl.

“Thioaryl” refers to the group —S-aryl and “substituted thioaryl” refersto the group —S-substituted aryl.

“Thioheteroaryl” refers to the group —S-heteroaryl and “substitutedthioheteroaryl” refers to the group —S-substituted heteroaryl.

“Thioheterocyclic” refers to the group —S-heterocyclic and “substitutedthioheterocyclic” refers to the group —S-substituted heterocyclic.

The term “amino acid” refers to α-amino acids of the formulaH₂NCH(R¹⁵)COOH where R¹⁵ is hydrogen, alkyl, substituted alkyl, aryl orsubstituted aryl. Preferably, the α-amino acid is one of the twentynaturally occurring L amino acids.

The term “carbohydrate” refers to oligosaccharides comprising from 2 to20 saccharide units. The particular saccharide units employed are notcritical and include, by way of example, all natural and syntheticderivatives of glucose, galactose, N-acetylglucosamine,N-acetylgalactosamine, fucose, sialic acid, and the like. In addition tobeing in their pyranose form, all saccharide units described herein arein their D form except for fucose which is in its L form.

The term “lipid” is an art recognized term defined, for example, byLehninger, Biochemistry, 1970, at pages 189 et seq. which isincorporated herein by reference in its entirety.

The term “peptide” refers to polymers of α-amino acids comprising fromabout 2 to about 20 amino acid units, preferably from about 2 to about10, more preferably from about 2 to about 5.

The term “stablilized phosphate prodrug” refers to mono-, di- andtri-phosphate groups having one or more of the hydroxyl groups pendentthereto converted to an alkoxy, a substituted alkoxy group, an aryloxyor a substituted aryloxy group.

The term “pharmaceutically acceptable prodrugs” refers to art recognizedmodifications to one or more functional groups which functional groupsare metabolized in vivo to provide a compound of this invention or anactive metabolite thereof. Such functional groups are well known in theart including acyl groups for hydroxyl and/or amino substitution, estersof mono-, di- and tri-phosphates wherein one or more of the pendenthydroxyl groups have been converted to an alkoxy, a substituted alkoxy,an aryloxy or a substituted aryloxy group, and the like.

“Pharmaceutically acceptable salt” refers to pharmaceutically acceptablesalts of a compound, which salts are derived from a variety of organicand inorganic counter ions well known in the art and include, by way ofexample only, sodium, potassium, calcium, magnesium, ammonium,tetraalkylammonium, and the like; and when the molecule contains a basicfunctionality, salts of organic or inorganic acids, such ashydrochloride, hydrobromide, tartrate, mesylate, acetate, maleate,oxalate and the like.

It is understood that in all substituted groups defined above, polymersarrived at by defining substituents with further substituents tothemselves (e.g., substituted aryl having a substituted aryl group as asubstituent which is itself substituted with a substituted aryl group,etc.) are not intended for inclusion herein. In such cases, the maximumnumber of such substituents is three. That is to say that each of theabove definitions is constrained by a limitation that, for example,substituted aryl groups are limted to -substituted aryl-(substitutedaryl)-substituted aryl.

Similarly, it is understood that the above definitions are not intendedto include impermissible substitution patterns (e.g., methyl substitutedwith 5 fluoro groups or a hydroxyl group alpha to ethenylic oracetylenic unsaturation). Such impermissible substitution patterns arewell known to the skilled artisan.

General Synthetic Methods

The compounds of this invention can be prepared from readily availablestarting materials using the following general methods and procedures.It will be appreciated that where typical or preferred processconditions (i.e., reaction temperatures, times, mole ratios ofreactants, solvents, pressures, etc.) are given, other processconditions can also be used unless otherwise stated. Optimum reactionconditions may vary with the particular reactants or solvent used, butsuch conditions can be determined by one skilled in the art by routineoptimization procedures.

Additionally, as will be apparent to those skilled in the art,conventional protecting groups may be necessary to prevent certainfunctional groups from undergoing undesired reactions. Suitableprotecting groups for various functional groups as well as suitableconditions for protecting and deprotecting particular functional groupsare well known in the art. For example, numerous protecting groups aredescribed in T. W. Greene and G. M. Wuts, Protecting Groups in OrganicSynthesis, Third Edition, Wiley, New York, 1999, and references citedtherein.

Furthermore, the compounds of this invention will typically contain oneor more chiral centers. Accordingly, if desired, such compounds can beprepared or isolated as pure stereoisomers, i.e., as individualenantiomers or diastereomers, or as stereoisomer-enriched mixtures. Allsuch stereoisomers (and enriched mixtures) are included within the scopeof this invention, unless otherwise indicated. Pure stereoisomers (orenriched mixtures) may be prepared using, for example, optically activestarting materials or stereoselective reagents well-known in the art,Alternatively, racemic mixtures of such compounds can be separatedusing, for example, chiral column chromatography, chiral resolvingagents and the like.

Still further, some of the compounds defined herein include vinyl groupswhich can exist in cis, trans or a mixture of cis and trans forms. Allcombinations of these forms are within the scope of this invention.

The starting materials for the following reactions are generally knowncompounds or can be prepared by known procedures or obviousmodifications thereof. For example, many of the starting materials areavailable from commercial suppliers such as Aldrich Chemical Co.(Milwaukee, Wis., USA), Bachem (Torrance, Calif., USA), Emka-Chemce orSigma (St. Louis, Mo., USA). Others may be prepared by procedures, orobvious modifications thereof, described in standard reference textssuch as Fieser and Fieser's Reagents for Organic Synthesis, Volumes 1-15(John Wiley and Sons, 1991), Rodd's Chemistry of Carbon Compounds,Volumes 1-5 and Supplementals (Elsevier Science Publishers, 1989),Organic Reactions, Volumes 1-40 (John Wiley and Sons, 1991), March'sAdvanced Organic Chemistry, (John Wiley and Sons, 4^(th) Edition), andLarock's Comprehensive Organic Transformations (VCH Publishers Inc.,1989). Specifically, the compounds of this invention may be prepared byvarious methods known in the art of organic chemistry in general andnucleoside and nucleotide analogue synthesis in particular. Generalreviews of the preparation of nucleoside and nucleotide analoguesinclude 1) Michelson A. M. “The Chemistry of Nucleosides andNucleotides,” Academic Press, New York, 1963; 2) Goodman L. “BasicPrinciples in Nucleic Acid Chemistry,” Academic Press, New York, 1974,vol. 1, Ch. 2; and 3) “Synthetic Procedures in Nucleic Acid Chemistry,”Eds. Zorbach W. & Tipson R., Wiley, New York, 1973, vol. 1 & 2.

The synthesis of the compounds of this invention generally followseither a convergent or linear synthetic pathway as described below.

The strategies available for synthesis of compounds of this inventioninclude for example:

General Synthesis of 2′-C-Branched Nucleosides

2′-C-Branched ribonucleosides of Formula I:

where R, W, W¹, W², Y, Y′ and Z are as defined above, can be prepared byone of the following general methods.

Convergent Approach: Glycosylation of Nucleobase with AppropriatelyModified Sugar

The key starting material of this process is an appropriatelysubstituted sugar with 2′-OH and 2′-H with the appropriate leavinggroup, for example, an acyl group or a chloro, bromo, fluoro or iodogroup. The sugar can be purchased or can be prepared by any known meansincluding standard epimerization, substitution, oxidation and/orreduction techniques. For example, commercially available1,3,5-tri-O-benzoyl-α-D-ribofuranose (Pfanstiel Laboratories, Inc.) canbe used. The substituted sugar can then be oxidized with the appropriateoxidizing agent in a compatible solvent at a suitable temperature toyield the 2′-modified sugar. Possible oxidizing agents are, for example,Dess-Martin periodine reagent, Ac₂O+DCC in DMSO, Swern oxidation (DMSO,oxalyl chloride, triethylamine), Jones reagent (a mixture of chromicacid and sulfuric acid), Collins's reagent (dipyridine Cr(VI) oxide,Corey's reagent (pyridinium chlorochromate), pyridinium dichromate, aciddichromate, potassium permanganate, MnO₂, ruthenium tetraoxide, phasetransfer catalysts such as chromic acid or permanganate supported on apolymer, C₁₂-pyridine, H₂O₂-ammonium molybdate, NaBrO₂—CAN, NaOCl inHOAc, copper chromite, copper oxide, Raney nickel, palladium acetate,Meerwin-Pondorf-Verley reagent (aluminum t-butoxide with another ketone)and N-bromosuccinimide.

Coupling of an organometallic carbon nucleophile, such as a Grignardreagent, an organolithium, lithium dialkylcopper or R¹—SiMe₃ in TBAFwith the ketone with the appropriate non-protic solvent at a suitabletemperature, yields the 2′-alkylated sugar. For example, R¹MgBr/TiCl₄ orR¹MgBr/CeCl₃ can be used as described in Wolfe et al., 1997. J. Org.Chem. 62: 1754-1759 (where R¹ is as defined herein). The alkylated sugarcan be optionally protected with a suitable protecting group, preferablywith an acyl, substituted alkyl or silyl group, by methods well known tothose skilled in the art, as taught by Greene et al. Protective Groupsin Organic Synthesis, John Wiley and Sons, Second Edition, 1991.

The optionally protected sugar can then be coupled to the purine base bymethods well known to those skilled in the art, as taught by TownsendChemistry of Nucleosides and Nucleotides, Plenum Press, 1994. Forexample, an acylated sugar can be coupled to a silylated base with aLewis acid, such as tin tetrachloride, titanium tetrachloride ortrimethylsilyltriflate in the appropriate solvent at a suitabletemperature. Alternatively, a halo-sugar can be coupled to a silylatedbase with the presence of trimethylsilyltriflate.

In addition to the above, the 2′-C-substituted sugars used in thesynthetic methods described herein are well known in the art and aredescribed, for example, by Sommadossi, et al.⁵ and by Carrol, et al.⁶both of which are incorporated herein by reference in their entirety.

Scheme 1 below describes the alternative synthesis of a protected sugarthat is useful for coupling to the bases described herein.Scheme 1: Alternative Sugar Synthesis and Coupling

Formation of sugar a in Scheme 1, above, is accomplished as described byMandal, S. B., et al., Synth. Commun., 1993, 9, page 1239, starting fromcommercial D-ribose. Protection of the hydroxyl groups to form sugar bis described in Witty, D. R., et al., Tet. Lett., 1990, 31, page 4787.Sugar c and d are prepared using the method of Ning, J. et al.,Carbohydr. Res., 2001, 330, page 165, and methods described herein. R¹,in Scheme 1 can be hydrogen, alkyl, substituted alkyl, alkenyl,substituted alkenyl, alkynyl, and substituted alkynyl. Particularlypreferred R¹ groups are methyl, trifluoromethyl, alkenyl and alkynyl.Sugar e is prepared by using a modification of the Grignard reactionwithn R¹MgBr or other appropriate organometallic as described herein(with no titanium/cerium needed). Finally the halogenated sugar used inthe subsequent coupling reaction is prepared using the same protectionmethod as used in to make sugar b above. The halogenation is describedin Seela.⁷

Subsequently, any of the described nucleosides can be deprotected bymethods well known to those skilled in the art, as taught by Greene etal Protective Groups in Organic Synthesis, Jon Wiley and Sons, SecondEdition, 1991.

An alternative approach to making protected sugars useful for couplingto heterocyclic bases is detailed in Scheme 2 below. The details forthis synthesis can be found in Example 1.

Linear Approach: Modification of a Pre-Formed Nucleoside

The key starting material for this process is an appropriatelysubstituted nucleoside with a 2′-OH and 2′-H. The nucleoside can bepurchased or can be prepared by any known means including standardcoupling techniques. The nucleoside can be optionally protected withsuitable protecting groups, preferably with acyl, substituted alkyl orsilyl groups, by methods well known to those skilled in the art, astaught by Greene et al. Protective Groups in Organic Synthesis, JohnWiley and Sons, Second Edition, 1991.

The appropriately protected nucleoside can then be oxidized with theappropriate oxidizing agent in a compatible solvent at a suitabletemperature to yield the 2′-modified sugar. Possible oxidizing agentsare, for example, Dess-Martin periodine reagent, Ac₂O+DCC in DMSO, Swernoxidation (DMSO, oxalyl chloride, triethylamine), Jones reagent (amixture of chromic acid and sulfuric acid), Collins's reagent(dipyridine Cr(VI) oxide, Corey's reagent (pyridinium chlorochromate),pyridinium dichromate, acid dichromate, potassium permanganate, MnO₂ruthenium tetroxide, phase transfer catalysts such as chromic acid orpermanganate supported on a polymer, Cl₂-pyridine, H₂O₂-ammoniummolybdate, NaBrO₂—CAN, NaOCl in HOAc, copper chromite, copper oxide,Raney nickel, palladium acetate, Meerwin-Pondorf-Verley reagent(aluminum t-butoxide with another ketone) and N-bromosuccinimide.Coupling of an organometallic carbon nucleophile, such as a Grignardreagent, an organolithium, lithium dialkylcopper or R¹—SiMe₃ in TBAFwith the ketone with the appropriate non-protic solvent at a suitabletemperature, yields the appropriate substituted nucleoside.

Subsequently, the nucleoside can be deprotected by methods well known tothose skilled in the art, as taught by Greene et al. Protective Groupsin Organic Synthesis, John Wiley and Sons, Second Edition, 1991.

In one embodiment of the invention, the L-enantiomers are preferred.However, D-enantiomers are also useful herein. The L-enantiomers can becorresponding to the compounds of the invention can be preparedfollowing the same foregoing general methods, beginning with thecorresponding L-sugar or nucleoside L-enantiomer as starting material.In a particular embodiment, the 2′-C-branched ribonucleoside is desired.In another embodiment, the 3′-C-branched ribonucleoside is desired.

Scheme 3 below provides a method for preparing 7-nitro-7-deazapurines ofthe present invention. The preparation of compound 115 from compound 102(prepared as in Scheme 2 above) and compound 101 has been describedelsewhere, (see Carroll, et al., International Patent ApplicationPublication No. WO 02/057425).

The hydroxyl groups of the 6-chloro-deazapurine derivative, compound115, are protected with acetyl groups by reaction with acetyl chlorideand acetic acid to form compound 115a. Compound 115a is converted to the7-nitor derivative reaction in a 5% (v/v) of an acid solution (1:1mixture of nitric and sulfuric acid solution) in DCM. The reaction isrun at about 0° C. to about room temperature for about 20 minutes, oruntil the reaction is complete. Hydroxylamine compounds of thisinvention are prepared by reaction of compound 116 with NH₂OH.Methoxyamine derivatives can be prepared in a similar manner usingNH₂OCH₃ in place of the NH₂OH.

Scheme 4, below provides a method for preparing 7-halo-7-deazapurinederivatives of the present invention. For example, reaction ofcommercially available compound 100 with NBS in acetonitrile, usingstandard conditions provides compound 101. Compound 104 is prepared bycoupling compound 101 with compound 103 (which is prepared as describedin Scheme 3 above). This coupling reaction is run in the presence ofsodium hydride in an inert solvent such as acetonitrile.

Deprotection of compound 104 is accomplished by reaction with BCl₃ inDCM at about −78° C. to about −20° C. for about 12 hours, providingcompound 105. Finally reaction of compound 105 withtrimethylsilyl-O-hydroxylamine in a solvent such as ethanol provides the7-halo-7-deazapurine derivatives. This reaction is run at about 85° C.for about 2 hours. These compounds are useful for the treatment of viralinfections, such as HCV. They are also useful as intermediates forpreparing other compounds of the present invention.

The 7-formyl-7-deazapurines of the present invention can be prepared asshown in Scheme 5 below. Compound 104 (prepared as discussed above) isreacted with carbon monoxide in the presence of a catalytic amounts oftributyltin hydride and palladium tetraphenylphosphine in an inertsolvent such as THF. This reaction is run for about 24 hours at about50° C. to provide compound 107. Deprotection of compound 107 asdescribed above provides for compound 109.

Reaction of compound 109 with trimethylsilyl-O-hydroxylamine, asdescribed above, provides for 6-hydroxylamine-7-formyl-7-deazapurines ofthe present invention.

Alternatively, reaction of compound 109 with NH₂OCH₃ in ethanol at about85° C. for about 2 hours provides compound 20,6-methoxyamino-7-formyl-7-deazapurine derivatives of the presentinvention.

Further, the formyl group of compound 109 can be used as an intermediatein the synthesis of alkenyl and substituted alkenyl compounds usingconventional Wittig-Homer reaction conditions.

Still further, the formyl group can be oxidized to provide for thecorresponding carboxyl group which, optionally, can be esterified byconventional methods to provide for a carboxyl ester or can be amidatedby conventional methods to provide for a carboxylamide, e.g.,—C(O)NR²¹R²¹ where R²⁰ and R²¹ are as defined above.

Preparation of the 7-cyano-7-deazapurine derivatives of the presentinvention are describe in Scheme 6 below. Compound 104 can be treatedwith tributyltin cyanide and palladium tetraphenylphosphine in an inertsolvent such as THF. This reaction is run for about 15 hours at about50° C. to provide for compound 111, which can be converted to thehydroxylamine or the methoxyamine as described above.

Acetylenic compounds of the present invention can be prepared by themethod shown in Scheme 7 below. The details for each reaction stepneeded to prepare compounds where X is —NHOH can be found in Example 2below. Specifically, reaction of compound 100 with NIS in a mannersimilar to that used with NBS in Scheme 4 provides for 7-iodosubstituent in compound 118. Coupling of this compound withtrimethylsilylacetylene to provide for compound 119 which itself iscoupled to sugar 102 under conventional conditions to provide forcompound 120. Conventional removal of protecting groups on the sugarprovides for compound 121 which is then converted to the hydroxylamineor the alkoxylamine and desilylated to provided for compound 122. Asbefore, conversion to the hydroxylamine employstrimethylsilyl-O-hydroxylamine and conversion to the alkoxyamine employstrialkylsilyl-O-methoxyamine in place of trimethylsilyl-O-hydroxylamine.

It is understood, of course, that the 7-iodo substituent is itself acompound of this invention as well as an intermediate in the synthesisof further compounds. Likewise, the 7-acetylenyl substitute can bederivatized by, e.g., hydrogenation, to provide for the correspondingvinyl compound (not shown).

Boronic substituents at the 7-position are prepared according to Scheme8 below. This methods used to prepare compound 125 are similar to thosediscussed for the preparation of compound 106 in Scheme 4 above. Asstated above, it is understood that the 7-iodo substituent is itself acompound of this invention as well as an intermediate in the synthesisof further compounds.

Conversion of compound 125 to the boronic acid derivative can beaccomplished using methods known in the art. For example by reactionwith an excess of KOAc (about 3 eq.) in the presence of about 3 mole %(Ph₃)₂PdCl₂ and about 1.2 eq. bis(neopenty glycolato)diiboron in aninert solvent such as DMSO (0.15M). This reaction is run at about 65° C.until complete.

Utility, Testing and Administration

Utility

The present invention provides novel compounds possessing antiviralactivity, including hepatitis C virus. The compounds of this inventioninhibit HCV replication by inhibiting the enzymes involved inreplication, including RNA dependent RNA polymerase. They may alsoinhibit other enzymes utilized in the activity or proliferation of HCV.

The compounds of the present invention can also be used as prodrugnucleosides. As such they are taken up into the cells and can beintracellularly phosphorylated by kinases to the triphosphate and arethen inhibitors of the polymerase (NS5b) and/or act aschain-terminators.

Compounds of this invention may be used alone or in combination withother compounds to treat viruses.

Administration and Pharmaceutical Composition

In general, the compounds of this invention will be administered in atherapeutically effective amount by any of the accepted modes ofadministration for agents that serve similar utilities. The actualamount of the compound of this invention, i.e., the active ingredient,will depend upon numerous factors such as the severity of the disease tobe treated, the age and relative health of the subject, the potency ofthe compound used, the route and form of administration, and otherfactors. The drug can be administered more than once a day, preferablyonce or twice a day.

Therapeutically effective amounts of compounds of this invention mayrange from approximately 0.05 to 50 mg per kilogram body weight of therecipient per day; preferably about 0.01-25 mg/kg/day, more preferablyfrom about 0.5 to 10 mg/kg/day. Thus, for administration to a 70 kgperson, the dosage range would most preferably be about 35-70 mg perday.

In general, compounds of this invention will be administered aspharmaceutical compositions by any one of the following routes: oral,systemic (e.g., transdermal, intranasal or by suppository), orparenteral (e.g., intramuscular, intravenous or subcutaneous)administration. The preferred manner of administration is oral using aconvenient daily dosage regimen that can be adjusted according to thedegree of affliction. Compositions can take the form of tablets, pills,capsules, semisolids, powders, sustained release formulations,solutions, suspensions, elixirs, aerosols, or any other appropriatecompositions. Another preferred manner for administering compounds ofthis invention is inhalation. This is an effective method for deliveringa therapeutic agent directly to the respiratory tract, in particular forthe treatment of diseases such as asthma and similar or relatedrespiratory tract disorders (see U.S. Pat. No. 5,607,915).

The choice of formulation depends on various factors such as the mode ofdrug administration and bioavailability of the drug substance. Fordelivery via inhalation the compound can be formulated as liquidsolution, suspensions, aerosol propellants or dry powder and loaded intoa suitable dispenser for administration. There are several types ofpharmaceutical inhalation devices-nebulizer inhalers, metered doseinhalers (MDI) and dry powder inhalers (DPI). Nebulizer devices producea stream of high velocity air that causes the therapeutic agents (whichare formulated in a liquid form) to spray as a mist that is carried intothe patient's respiratory tract. MDI's typically are formulationpackaged with a compressed gas. Upon actuation, the device discharges ameasured amount of therapeutic agent by compressed gas, thus affording areliable method of administering a set amount of agent. DPI dispensestherapeutic agents in the form of a free flowing powder that can bedispersed in the patient's inspiratory air-stream during breathing bythe device. In order to achieve a free flowing powder, the therapeuticagent is formulated with an excipient such as lactose. A measured amountof the therapeutic agent is stored in a capsule form and is dispensedwith each actuation.

Recently, pharmaceutical formulations have been developed especially fordrugs that show poor bioavailability based upon the principle thatbioavailability can be increased by increasing the surface area i.e.,decreasing particle size. For example, U.S. Pat. No. 4,107,288 describesa pharmaceutical formulation having particles in the size range from 10to 1,000 nm in which the active material is supported on a crosslinkedmatrix of macromolecules. U.S. Pat. No. 5,145,684 describes theproduction of a pharmaceutical formulation in which the drug substanceis pulverized to nanoparticles (average particle size of 400 nm) in thepresence of a surface modifier and then dispersed in a liquid medium togive a pharmaceutical formulation that exhibits remarkably highbioavailability.

The compositions are comprised of in general, a compound of thisinvention or a mixture thereof in combination with at least onepharmaceutically acceptable excipient. Acceptable excipients arenon-toxic, aid administration, and do not adversely affect thetherapeutic benefit of the compound of this invention. Such excipientmay be any solid, liquid, semi-solid or, in the case of an aerosolcomposition, gaseous excipient that is generally available to one ofskill in the art.

Solid pharmaceutical excipients include starch, cellulose, talc,glucose, lactose, sucrose, gelatin, malt, rice, flour, chalk, silicagel, magnesium stearate, sodium stearate, glycerol monostearate, sodiumchloride, dried skim milk and the like. Liquid and semisolid excipientsmay be selected from glycerol, propylene glycol, water, ethanol andvarious oils, including those of petroleum, animal, vegetable orsynthetic origin, e.g., peanut oil, soybean oil, mineral oil, sesameoil, etc. Preferred liquid carriers, particularly for injectablesolutions, include water, saline, aqueous dextrose, and glycols.

Compressed gases may be used to disperse a compound of this invention inaerosol form. Inert gases suitable for this purpose are nitrogen, carbondioxide, etc. Other suitable pharmaceutical excipients and theirformulations are described in Remington's Pharmaceutical Sciences,edited by E. W. Martin (Mack Publishing Company, 18th ed., 1990).

The amount of the compound in a formulation can vary within the fullrange employed by those skilled in the art. Typically, the formulationwill contain, on a weight percent (wt %) basis, from about 0.01-99.99 wt%/o of a compound of this invention based on the total formulation, withthe balance being one or more suitable pharmaceutical excipients.Preferably, the compound is present at a level of about 1-80 wt %.Representative pharmaceutical formulations containing a compound of thisinvention are described below.

Dosages and Ranges of Compounds

The amount of the composition administered for therapeutic will dependon a number of factors, including but not limited to the desired finalconcentration of the compound, the pharmacokinetic and pharmacodynamicproperties of the compound, the size of the patient, physiologicalprofile of the patient, and the like. The active compound is effectiveover a wide dosage range and is generally administered in apharmaceutically effective amount. It, will be understood, however, thatthe amount of the compound actually administered will be determined by aphysician, in the light of the relevant circumstances, including thecondition to be treated, the chosen route of administration, the actualcompound administered, the age, weight, and response of the individualpatient, the severity of the patient's symptoms, and the like.

Determination of dosages is well within the empiric knowledge of personsskilled in the art; nonetheless, it can be appreciated that estimates offinal dosages can be made by approximating the concentration of compoundnecessary to achieve a desired proteasomic inhibitory,anti-proliferative, anti-cancer or anti-inflammatory activity, such asthe activities described above. Further refinement of this dose estimatecan be made on the basis of activity in one or more preclinical models,such as the animal models exemplified in Example 16 herein.Extrapolation to a specified mammalian dosage range, or moreparticularly a human dosage range is well within the skill of thepractitioner.

Typically, the amount of a single administration of a composition of thepresent invention can be about 0.1 to about 1000 mg per kg body weight,or about 0.5 to about 10,000 mg per day. Any of these doses can befurther subdivided into separate administrations, and multiple dosagescan be given to any individual patient.

In some embodiments, compositions are administered in one dosing of asingle formulation and in other embodiments, compositions areadministered in multiple dosing of a single formulation within aspecified time period. In some embodiments, the time period is betweenabout 3 hours to about 6 hours. In other embodiments, the time period isbetween about 6 hours and 12 hours. In additional embodiments, the timeperiod is between about 12 hours and 24 hours. In yet furtherembodiments, the time period is between about 24 hours and 48 hours. Theadministration of separate formulations can be simultaneous or stagedthroughout a specified time period, such that all ingredients areadministered within the specified time period.

EXAMPLES

The examples below as well as throughout the application, the followingabbreviations have the following meanings. If not defined, the termshave their generally accepted meanings. AcOH or HOAc = acetic acid Ac₂O= acetic anhydride atm = atmosphere CAN = ceric ammonium nitrate cm =centimeter d = doublet dd = doublet of doublets dec = decomposes DCB =2,4,-dichlorobenzyl DCC = N,N-dicyclohexyl carbodiamide DCM =dichloromethane DMAP = dimethylaminopyridine DMEM = Delbecco's minimumeagles medium DMF = N,N-dimethylformamide DMSO = dimethylsulfoxide DTT =dithiothreitol EDTA = ethylene diamine tetraacetic acid eq. or equiv. =equivalents g = gram h = hour HCV = hepatitis C virus HPLC = highperformance liquid chromatography IPTG =isopropyl-b-D-thiogalactopyranoside IU = international units kb =kilobase kg = kilogram L = liter m = multiplet M = molar mg = milligrammL or ml = milliliter mM = millimolar mmol = millimol MS = mass spectrumng = nanograms nm = nanometers nM = nanomolar NBS = N-bromosuccinimideNIS = N-iodosuccinimide NMR = nuclear magnetic resonance NTA =nitrilotriacetic acid NTP = nucleotide triphosphate RP HPLC = reversephase high performance liquid chromatography s = singlet TBAF =tetrabutylammonium fluoride THF = tetrahydrofuran TFA = trifluoroaceticacid T_(m) = temperature of melting μL = microliters v/v = volume tovolume +wt % = weight percent μg = micrograms μM = micromolar

In addition, all reaction temperatures are in degrees Celcius unlessreported otherwise and all percentages are molar percents again unlessindicated otherwise.

Example 1 Preparation of the Intermediate1-O-methyl-2-methyl-3,5-bis-O-(2,4-dichlorobenzyl)-β-D-ribosfuranose

Step 1: Preparation of1-O-methyl-2,3,5-tris-O-(2,4-dichlorobenzyl)-β-D-ribofuranose

The title compound is synthesized using the methods described in Martin,P.; Helv. Chim. Acta, 1995, 78, 486 starting with commercially availableD-ribose.

Step 2: Preparation of1-O-methyl-3,5-bis-O-(2,4-dichlorobenzyl)-β-D-ribofuranose

To a solution of the product of Step 1 (171.60 g, 0.2676 mol) in 1.8 LCH₂Cl₂ that was cooled to 0° C., was added dropwise a solution ofstannous chloride (31.522 mL, 0.2676 mol) in 134 mL CH₂Cl₂ whilestirring. After the solution was kept at 3° C. for 27 hours, another5.031 ml of SnCl₄ (0.04282 mol) was added and the solution was kept at3° C. overnight. After 43 hours the reaction was quenched by carefullyadding the solution to 1.9 L saturated NaHCO₃ solution. Tin salts wereremoved via filtration through celite after which the organic phace wasisolated, dried with MgSO₄ and evaporated in vacuo. The yield of raw,dark yellow oil was 173.6 g, which contains 2,4-dibenzoyl chloride. Thecrude oil was used directly in the next step without furtherpurification.

Step 3: Preparation of1-O-methyl-2-oxo-3,5-bis-O-(2,4-dichlorobenzl)-β-D-ribofuranose

To an ice-cold suspension of Dess-Martin periodinane (106.75 g, 0.2517mol) in 740 mL anhydrous CH₂Cl₂, under argon, was added a solution ofthe product of Step 2 above in 662 mL anhydrous CH₂Cl₂ dropwise over 0.5hours. The reaction mixture was stirred at 0° C. for 0.5 hours and thenat room temperature for 6 days. The mixture was diluted with 1.26 Lanhydrous Et₂O and poured into an ice-cold mixture of Na₂S₂O₃5H₂O (241.2g, 1.5258 mol) in 4.7 L saturated aqueous NaHCO₃. The layers wereseparated, and the organic layer was washed with 1.3 L saturated aqueousNaHCO₃, 1.7 L water and 1.3 L brine, dried with MgSO₄, filtered andevaporated to give the target compound. This compound (72.38 g, 0.1507mol) was used without further purification in the next step.

Step 4: Preparation of the Title Compound

A solution of MeMgBr in 500 mL anhydrous Et₂O at 55° C. was addeddropwise to a solution of the product of Step 3 above (72.38 g, 0.1507mol), also in 502 mL anhydrous Et₂O. The reaction mixture was allowed towarm to −30° C. and stirred mechanically for 4 hours at −30° C. to −15°C., then poured into 2 L ice cold water. After stirring vigorously atambient temperature for 0.5 hours, the mixture was filtered through aCelite pad (14×5 cm), which was thoroughly washed with Et₂O. The organiclayer was dried with MgSO₄, filtered and concentrated in vacuo. Theresidue was dissolved in hexanes (˜1 mL per gram crude), applied to asilica gel column (1.5 L silica gel in hexanes) and eluted with hexanesand [4:1 hexanes:ethyl acetate, v/v] to give 53.58 g (0.1080 mol) of thefinal purified product. The morphology of the title compound was that ofan off-yellow, viscous oil.

MS: m/z 514.06 (M+NH₄+).

Example 2 Preparation of1-(6-Hydroxylamino-7-ethynyl-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose

Step 1: Synthesis of 6-Chloro-7-iodo-7-deazapurine:

6-Chloro-7-deazapurine 10.75 g (70 mmol) and N-iodosuccinimide (16.8 g,75 mmol) were dissolved in 400 ml of dry DMF and left at ambienttemperature in the darkness over night. The solvent was evaporated. Thedark residue was distributed between 500 ml of ethyl acetate and 150 mlof 10% Na₂SO₃. Organic fraction was washed with 10% Na₂SO₃ (2×100 ml),brine (150 ml), dried over Na₂SO₄ and evaporated. The yellow residue wascrystallized from ethanol to yield 16.2 g (83%) of the title compound asoff white crystals. The mother liquid was evaporated, dissolved intoluene, and purified by flush chromatography on silica gel (7×4 cm).The column was washed with toluene until the eluent was colorless thanthe title compound was eluted with 5% ethyl acetate in toluene to giveadditional 3.5 g of the title product.

Total yield is 98%.

T_(m) 212-214 (dec)

UV λ_(max): 307, 266, 230, 227 nm (methanol)

MS: 277.93 (M−H), 313 (M+Cl)

¹H-NMR (DMSO-d₆): δ 12.94 (s, 1H, NH), 8.58 (s, 1H, H-2), 7.94 (s, 1H,H-8)

Step 2: Synthesis of 6-Chloro-7-trimethylsilanylethynyl-7-deazapurine:

The heterocycle obtained in Step 1 above (16 g, 64.25 mmol) was dried byco-evaporation with dry DMF (2×50 ml) and dissolved in DMF/THF mixture(800 ml, 1:3 v/v). Triethylamine (8.33 ml, 0.93 equiv.), CuI (4.9 g, 0.4equiv.) and (trimethylsilyl) acetylene (54.5 ml, 6 equiv.) were added.The flask was filled with Ag then (Ph₃)₄Pd (7.4 g, 0.1 equiv.) was addedand the mixture was left over night at ambient temperature. The solventwas evaporated; the dark residue was distributed between 1000 ml ofethyl acetate and 300 ml of water. Organic fraction was washed withbrine (2×150 ml), dried over Na₂SO₄ and concentrated up to the volume200 ml. Dry silica gel was added to the solution (about 400 ml) and themixture was evaporated to dryness. The silica gel caring the reactionmixture was loaded onto the filter, containing silica gel in toluene(6×13 cm, about 1000 ml of silica gel). The filter was washed withtoluene until the eluent was colorless; compound was eluted withtoluene/ethyl acetate (9:1 v/v, 5 l). Solvent was evaporated andcompound crystallized from acetone/hexane. The title compound wasobtained by recrystallization from methanol. The 9.8 g of first crop wasobtained as tan crystals; the second crop was 2.3 g, also tan crystals.Total yield 12.1 g (85%).

Tm 217-220 (dec)

UV λ_(max) : 311, 245, 239, 231 nm (methanol)

MS: 248.07 (M-H),

¹H-NMR (DMSO-d₆): δ 12.92 (s, 1H, NH), 8.60 (s, 1H, H-2), 8.06 (s, 1H,H-8)

Step 3: Synthesis of1-(6-Chloro-7-trimethylsilanylethynyl-7-deazapurin-9-yl)-2-methyl-3,5-di(-O-2,4-dichlorobenzyl)-β-D-ribofuranose:

The base, obtained as described in Step 2 above (9.8 g, 39 mmol) wassuspended in 600 ml of CH₃CN, NaH was added (1.6 g, 39 mmol 60% in oil)and the reaction mixture was stirred at room temperature until the clearsolution was formed (about 1 hour).1-O-Methyl-2-methyl-3,5-di(-O-2,4-dichlorobenzyl)-β-D-ribofuranose (10g, 20 mmol) was dissolved in 500 ml of DCM and cooled down to 4° C. inice/water bath. HBr/AcOH (30 ml) was added dropwise, reaction mixturewas kept in the bath for 1 hour more, solvents were evaporated andco-evaporated with dry toluene (2×50 ml), keeping all time thetemperature below 25° C. The dark residue was dissolved in CH₃CN (100ml) and added to the solution of Na-salt of the base. The reaction waskept overnight at ambient temperature. The solvent was evaporated andthe dark residue was distributed between 1000 ml of ethyl acetate and300 ml of 5% solution of citric acid. Organic fraction was washed withwater (150 ml), brine (150 ml), dried over Na₂SO₄ and concentrated up tothe volume 200 ml. Dry silica gel was added to the solution (about 400ml) and the mixture was evaporated to dryness. The silica gel caring thereaction mixture was loaded onto the column (5×20 cm), packed in hexane.The column was washed with 10% EtOAc in hexane to elute first the sideproduct—6-Chloro-7-trimethylsilanylethynyl-9-(2,4-dichlorobenzyl)-7-deazapurine;then the title compound was eluted. The elution was continued with 20%EtOAc/hexane to recover unreacted base as white crystals. The yield ofthe title compound 10.9 g, 76% as tan foam.

¹H-NMR (DMSO-d₆): δ 8.75 (s, 1H, H-2), 8.20 (s, 1H, H-8), 7.63-7.38 (m,6H, dichlorophenyl), 6.22 (s, 1H, H-1′), 5.65 (s, 1H, H-3′), 4.80-4.45(m, 4H, CH₂-benzyl, 2′-OH, H-4′), 4.21 (s, 2H, CH₂-benzyl), 3.97 and3.80 (dd, 1H, H-5′), 0.92 (s, 3H, 2′-methyl), 0.23 (s, 9H, Si(CH₃)₃)

Step 4: Synthesis of1-(6-Chloro-7-trimethylsilanylethynyl-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose:

To the solution of the compound from the previous step (5.4 g, 7.5 mmol)in DCM (200 ml) at −78° C. was added boron trichloride (1M in DCM, 88mL, 88 mmol) dropwise. The mixture was stirred at −78° C. for 2.5 hoursand additionally 3 h at −20 to −30° C. The reaction was quenched byaddition of methanol/DCM (90 mL, 1:1) and the resulting mixture stirredat −20° C. for 30 min, then neutralized by aqueous ammonia at the sametemperature. The solid was filtered and washed with methanol/DCM (250mL, 1:1). The combined filtrates were evaporated, and the residue waspurified by chromatorgapy on silica gel using for elution chloroform andthen chloroform/methanol from 2% to 10% as step gradient. The desiredcompound was obtained as yellowish foam, the yield 2.2 g (75%).

¹H-NMR (DMSO-d6 δ0.70 (s, 11H, H-2), 8.45 (s, 11H, H-8), 6.21 (s, 1H,H-1′), 5.40-5.20 (m, 3H, sugar), 4.00-3.60 (m, 4H, sugar), 0.84 (s, 3H,2′-methyl), 0.23 (s, 9H; Si(CH₃)₃)

Step 5: Synthesis of1-(6-hydroxylamino-7-ethynyl-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose:

Dry 6-chloro nucleoside from Step 4 above (300 mg, 1 mmol) was dissolvedin dry ethanol, trimethylsilyl-O-hydroxylamine was added (300 mg) andreaction mixture was refluxed for 5 hours. Reaction was controlled byLC-MS. When no starting nucleoside was detected the mixture was cooleddown to room temperature, neutralized with HCl/dioxane and evaporated todryness. The residue was purified by RP HPLC 0% to 100% B in 20 min.A-0.05% TFA in water, B-0.05% TFA in acetonitrile, flow rate 10 ml/min.The first peak was collected and evaporated to dryness. The residue wasdissolved in methanol, 200 ul of HCl/dioxane was added and solvents wereevaporated. The residue was dissolved in 3 ml of methanol andprecipitated by 35 ml of ether to yield 150 mg (50%) of the titlecompound as off-white powder.

MS: 321.11 (M+H)

¹H-NMR (DMSO-d₆): δ 0.86 (s, 3H, CH3); 5.99 (s, 1H, H-1′); 7.88 and 7.92(s, 1H, base).

Example 3 Preparation of1-(6-hydroxylamino-7-ethenyl-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose

1-(6-Hydroxylamino-7-ethynyl-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose(Example 2) is dissolved in THF and placed under hydrogen (1 atm) in thepresence of Lindlar's catalyst until one mole of hydrogen is consumed toprovide the title compound.

Biological Examples Example 1 Anti-Hepatitis C Activity

Compounds of this invention exhibit anti-hepatitis C activity byinhibiting HCV polymerase, by inhibiting other enzymes needed in thereplication cycle, or by other pathways. A number of assays have beenpublished to assess these activities. A general method that assesses thegross increase of HCV virus in culture is disclosed in U.S. Pat. No.5,738,985 to Miles et al In vitro assays have been reported in Ferrariet al Jnl. of Vir., 73:1649-1654, 1999; Ishii et al, Hepatology,29:1227-1235, 1999; Lohmann et al., Jnl of Bio. Chem., 274:10807-10815,1999; and Yamashita et al., Jnl of Bio. Chem., 273:15479-15486, 1998.

WO 97/12033, filed on Sep. 27, 1996, by Emory University, listing C.Hagedorn and A. Reinoldus as inventors, which claims priority to U.S.Ser. No. 60/004,383, filed on September 1995, describes an HCVpolymerase assay that can be used to evaluate the activity of the of thecompounds described herein. Another HCV polymerase assay has beenreported by Bartholomeusz, et al, Hepatitis C Virus (HCV) RNA polymeraseassay using cloned HCV non-structural proteins; Antiviral Therapy1996:1(Supp 4) 18-24.

Screens that measure reductions in kinase activity from HCV drugs aredisclosed in U.S. Pat. No. 6,030,785, to Katze et al., U.S. Patent No.Delvecchio et al, and U.S. Pat. No. 5,759,795 to Jubin et at Screensthat measure the protease inhibiting activity of candidate HCV drugs aredisclosed in U.S. Pat. No. 5,861,267 to Su et al, U.S. Pat. No.5,739,002 to De Francesco et al, and U.S. Pat. No. 5,597,691 to Houghtonet al

Example 2 Replicon Assay

A cell line, ET (Huh-lucubineo-ET) was used for screening of compoundsof the present invention for HCV RNA dependent RNA polymerase. The ETcell line was stably transfected with RNA transcripts harboring a1₃₈₉luc-ubi-neo/NS3-3′/ET; replicon with fireflyluciferase-ubiquitin-neomycin phosphotransferase fusion protein andEMCV-IRES driven NS3-5B polyprotein containing the cell culture adaptivemutations (E1202G; T12801; K1846T) (Krieger at al, 2001 andunpublished). The ET cells were grown in DMEM, supplemented with 10%fetal calf serum, 2 mM Glutamine, Penicillin (100 IU/mL)/Streptomycin(100 μg/ml), 1× nonessential amino acids, and 250 μg/mL G418(“Geneticin”). They are all available through Life Technologies(Bethesda, Md.). The cells were plated at 0.5-1.0×10⁴ cells/well in the96 well plates and incubated for 24 h before adding nucleoside analogs.Then the compounds each at 5 and 50 μM were added to the cells.Luciferase activity was measured 48-72 hours later by adding a lysisbuffer and the substrate (Catalog number Glo-lysis buffer E2661 andBright-Glo leuciferase system E2620 Promega, Madison, Wis.). Cellsshould not be too confluent during the assay. Percent inhibition ofreplication was plotted relative to no compound control. Under the samecondition, cytotoxicity of the compounds was determined using cellproliferation reagent, WST-1 (Roche, Germany). The compounds showingantiviral activities, but no significant cytotoxicities are chosen todetermine IC₅₀ and TC₅₀.

Example 3 Cloning and Expression of Recombinant HCV-NS5b

The coding sequence of NS5b protein was cloned by PCR frompFKI₃₈₉luc/NS3-3′/ET as described by Lohmann, V., et al. (1999) Science285, 110-113 using the following primers:

-   -   aggacatggatccgcggggtcgggcacgagacag (SEQ. ID. NO. 1)    -   aaggctggcatgcactcaatgtcctacacatggac (SEQ. ID. NO. 2)

The cloned fragment was missing the C terminus 21 amino acid residues.The cloned fragment was inserted into an IPTG-inducible expressionplasmid that provides an epitope tag (His)₆ at the carboxy terminus ofthe protein.

The recombinant enzyme was expressed in XL-1 cells and after inductionof expression, the protein was purified using affinity chromatography ona nickel-NTA column. Storage condition is 10 mM Tris-HCl pH 7.5, 50 mMNaCl, 0.1 mM EDTA, 1 mM DTT, 20% glycerol at −20° C.

Example 4 HCV-NS5b Enzyme Assay

The polymerase activity is assayed by measuring incorporation ofradiolabeled UTP into a RNA product using a poly-A template (1000-10000nucleotides) and oligo-U₁₂ primer. Alternatively, a portion of the HCVgenome is used as template and radiolabeled GTP is used. Typically, theassay mixture (50 μL) contains 10 mM Tris-HCl (pH7.5), 5 mM MgCl₂, 0.2mM EDTA, 10 mM KCl, 1 unit/μL RNAsin, 1 mM DTT, 10 μM each of NTP,alpha-[³²P]-GTP, 10 ng/μL polyA template and 1 ng/μL oligoU primer. Testcompounds are dissolved in water containing 0 to 1% DMSO. Typically,compounds are tested at concentrations between 1 nM and 100 μM.Reactions are started with addition of enzyme and allowed to continue atroom temperature or 30° C. for 1 to 2 h. Reactions are quenched with 20μL 10 mM EDTA and reaction mixtures (50 μL) spotted on DE81 filter discto capture the radiolabelled RNA products. After washing with 0.5 mMNa₂HPO₄ (3 times), water (1 time) and ethanol (1 time) to removeunincorporated NTP, the discs are dried and the incorporation ofradioactivity is determined by scintillation counting.

Formulation Examples

The following are representative pharmaceutical formulations containinga compound of Formula IV or IVA.

Example 1 Tablet Formulation

The following ingredients are mixed intimately and pressed into singlescored tablets. Quantity per Ingredient tablet, mg compound of thisinvention 400 cornstarch 50 croscarmellose sodium 25 lactose 120magnesium stearate 5

Example 2 Capsule Formulation

The following ingredients are mixed intimately and loaded into ahard-shell gelatin capsule. Quantity per Ingredient capsule, mg compoundof this invention 200 lactose, spray-dried 148 magnesium stearate 2

Example 3 Suspension Formulation

The following ingredients are mixed to form a suspension for oraladministration. Ingredient Amount compound of this invention 1.0 gfumaric acid 0.5 g sodium chloride 2.0 g methyl paraben 0.15 g propylparaben 0.05 g granulated sugar 25.0 g sorbitol (70% solution) 13.00 gVeegum K (Vanderbilt Co.) 1.0 g flavoring 0.035 ml colorings 0.5 mgdistilled water q.s. to 100 ml

Example 4 Injectable Formulation

The following ingredients are mixed to form an injectable formulation.Ingredient Amount compound of this invention 0.2 mg-20 mg sodium acetatebuffer solution, 0.4 M 2.0 ml HCl (1N) or NaOH (1N) q.s. to suitable pHwater (distilled, sterile) q.s. to 20 ml

Example 5 Suppository Formulation

A suppository of total weight 2.5 g is prepared by mixing the compoundof the invention with Witepsol® H-15 (triglycerides of saturatedvegetable fatty acid; Riches-Nelson, Inc., New York), and has thefollowing composition: Ingredient Amount compound of the invention 500mg Witepsol ® H-15 balance

From the foregoing description, various modifications and changes in theabove described invention will occur to those skilled in the art. Allsuch modifications coming within the scope of the appended claims areintended to be included therein.

1. A compound of Formula I below:

wherein: W, W¹ and W² are independently selected from the groupconsisting of hydrogen and a pharmaceutically acceptable prodrug; R isselected from the group consisting of hydrogen or (C₁-C₃)alkyl; R¹ isselected from the group consisting of hydrogen, alkyl, substitutedalkyl, alkenyl, substituted alkenyl, alkynyl and substituted alkynyl; Yis a bond, —CH₂— or —O—; Y′ is selected from the group consisting ofhydrogen, halo, hydroxyl, thioalkyl, amino and substituted amino; Z isselected from the group consisting of acyl, cyano, carboxyl, carboxylester, —C(O)NR²⁰R²¹, halo, —B(OH)₂, —C(═NR²)R³, nitro, alkenyl,substituted alkenyl, acetylenyl and substituted acetylenyl of theformula —C≡C—R⁴; where R² is selected from the group consisting ofhydrogen, —OH, —OR⁵ amino, substituted amino, and (C₁-C₂)alkyl, where R⁵is selected from the group consisting of alkyl and substituted alkyl; R³is selected from the group consisting of hydrogen, alkyl, substitutedalkyl, amino and substituted amino; R⁴ is selected from the groupconsisting of hydrogen, phenyl, substituted phenyl, heteroaryl,substituted heteroaryl, —Si(R⁸)₃, carboxyl, carboxyl esters, and—C(O)NR⁶R⁷ where R⁶ and R⁷ are independently hydrogen, alkyl or R⁶ andR⁷ together with the nitrogen atom pendent thereto are joined to form aheterocyclic, substituted heterocyclic, heteroaryl or substitutedheteroaryl group; each R⁸ is independently (C₁-C₄)alkyl or phenyl; andR²⁰ and R²¹ are independently hydrogen, alkyl, substituted alkyl, aryl,substituted aryl, heteroaryl, substituted heteroaryl, heterocyclic andsubstituted heterocyclic or R²⁰ and R²¹, together with the nitrogen atompendent thereto form a heterocyclic or substituted heterocyclic group;or pharmaceutically acceptable salts thereof.
 2. A compound of claim 1wherein, W is selected from the group consisting of hydrogen,monophosphate, diphosphate, and triphosphate.
 3. A compound of claim 1wherein, W¹ and W² are independently hydrogen or acyl.
 4. A compound ofclaim 3, wherein one of W¹ and W² is an acyl group selected from thegroup consisting of acetyl, trimethylacetyl, and acyl groups derivedfrom amino acids.
 5. A compound of Formula II

wherein: W is selected from the group consisting of hydrogen and apharmaceutically acceptable prodrug; R is selected from the groupconsisting of hydrogen or (C₁-C₃)alkyl; Z is selected from the groupconsisting of acyl, cyano, carboxyl, carboxyl ester, —C(O)NR²R²¹, halo,—B(OH)₂, —C(═NR²)R³, nitro, alkenyl, substituted alkenyl, acetylenyl andsubstituted acetylenyl of the formula —C≡C—R⁴; where R² is selected fromthe group consisting of hydrogen, —OH, —OR⁵ amino, substituted amino,and (C₁-C₂)alkyl, where R⁵ is selected from the group consisting ofalkyl and substituted alkyl; R³ is selected from the group consisting ofhydrogen, alkyl, substituted alkyl, amino and substituted amino; R⁴ isselected from the group consisting of hydrogen, phenyl, substitutedphenyl, heteroaryl, substituted heteroaryl, —Si(R⁸)₃, carboxyl, carboxylesters, and —C(O)NR⁶R⁷ where R⁶ and R⁷ are independently hydrogen, alkylor R⁶ and R⁷ together with the nitrogen atom pendent thereto are joinedto form a heterocyclic, substituted heterocyclic, heteroaryl orsubstituted heteroaryl group; each R⁸ is independently (C₁-C₄)alkyl orphenyl; and R²⁰ and R²¹ are independently hydrogen, alkyl, substitutedalkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl,heterocyclic and substituted heterocyclic or R²⁰ and R²¹, together withthe nitrogen atom pendent thereto form a heterocyclic or substitutedheterocyclic group; or pharmaceutically acceptable salts thereof.
 6. Acompound of claim 5 wherein, W is selected from the group consisting ofhydrogen, monophosphate, diphosphate, and triphosphate.
 7. A compound ofclaim 1 or claim 5, wherein, Z is selected from the group consisting ofacyl, nitro, halo, cyano, —C(═NR²)R³, acetylenyl and substitutedacetylenyl of the formula —C≡C—R⁴ where R², R³ and R⁴ are as definedabove.
 8. A compound of claim 7 wherein, Z is selected from formyl,nitro, bromro, iodo, and —C≡C—R⁴ and R⁴ is selected from H, phenyl, and—Si(CH₃)₃.
 9. A compound selected from the group consisting of:1-(6-hydroxylamino-7-ethynyl-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose(1);1-(6-hydroxylamino-7-(2-phenylethyn-1-yl)-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose(2);1-(6-hydroxylamino-7-(2-(pyridin-2-yl)-ethyn-1-yl)-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose(3);1-(6-hydroxylamino-7-(2-(4-fluorophenyl)ethyn-1-yl)-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose(4);1-(6-hydroxylamino-7-(2-(4-methylphenyl)ethyn-1-yl)-7-deaza-purin-9-yl)-2-methyl-β-D-ribofuranose(5);1-(6-hydroxylamino-7-(2-carboxylethyn-1-yl)-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose(6); 1-(6-hydroxylamino-7-(2-ethylcarboxylethyn-1-yl)-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose (7);1-(6-hydroxylamino-7-(2-carboxamidoethyn-1-yl)-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose(8);1-(6-hydroxylamino-7-(2-trimethylsilylethyn-1-yl)-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose(9);1-(6-hydroxylamino-7-ethenyl-7-deaza-purin-9-yl)-2-methyl-β-D-ribofuranose(10);1-(6-hydroxylamino-7-formyl-7-deaza-purin-9-yl)-2-methyl-β-D-ribofuranose(11); 1-(6-hydroxylamino-7-(carbaldehydeoxime))-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose (12);1-(6-hydroxylamino-7-(boronicacid)-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose (13);1-(6-hydroxylamino-7-(2,2-difluorovinyl)-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose(14);1-(6-hydroxylamino-7-(2-cis-methoxyvinyl)-7-deazapurin-9-yl)-2-methy-β-D-ribofuranose(15);1-(6-hydroxylamino-7-nitro-7-deaza-purin-9-yl)-2-methyl-β-D-ribofuranose(16);1-(6-hydroxylamino-7-cyano-7-deaza-purin-9-yl)-2-methyl-β-D-ribofuranose(17);1-(6-methoxyamino-7-ethynyl-7-deazapurin-9-yl)-2-methyl-β-D-ribofuranose(18);1-(6-methoxyamino-7-nitro-7-deaza-purin-9-yl)-2-methyl-β-D-ribofuranose(19);1-(6-methoxyamino-7-formyl-7-deaza-purin-9-yl)-2-methyl-β-D-ribofuranose(20); and pharmaceutically acceptable salts thereof.
 10. Apharmaceutical compositions comprising a pharmaceutically acceptablediluent and a therapeutically effective amount of a compound of any oneof claims 1, 5 and
 9. 11. A method for treating a viral infectionmediated at least in part by a virus in the flaviviridae family ofviruses in mammals which methods comprise administering to a mammal,that has been diagnosed with said viral infection or is at risk ofdeveloping said viral infection, a pharmaceutical composition comprisinga pharmaceutically acceptable diluent and a therapeutically effectiveamount of a compound of any one of claims 1, 5 and
 9. 12. The method ofclaim 11, wherein said virus is HCV.